HYDROXYL RADICAL GENERATION IN RAT-BRAIN IS INITIATED BY IRON BUT NOTALUMINUM, AS DETERMINED BY MICRODIALYSIS WITH SALICYLATE TRAPPING ANDGC-MS ANALYSIS

Free radical-induced bra in oxidative injury is thought to play a role in the etiology and pathogenesis of neurodegenerative disorders. iron (Fe)can catalyze the Fenton reaction and mediate hydroxyl radical (HO .) generation to initiate lipid peroxidation (LP). The neurotoxin alum inum (Al) can facilitate Fe-mediated LP. However, the mechanism of Al- facilitated LP has not been determined. In this study, microdialysis ( MD) of the ventral hippocampus was performed in rats exposed to Fe and /or Al sulfate via the MD probe. Salicylate (SA) was in eluded in the dialysate to trap the HO. by forming 2 3-dihydroxybenzoic acid (2,3-DH BA). 2,3-DHBA was quantified by capillary column gas chromatography-ma ss spectrometry (GC-MS) as a trimethylsilyl (TMS) derivative with 2,4- DHBA as an internal standard. Fe-catalyzed HO. generation was shown in brain interstitial fluid. Aluminum alone did not initiate HO. generat ion. Al did not facilitate Fe-catalyzed HO. generation. Therefore, the previously reported Al facilitation of Fe-mediated oxidative injury m ust be due to mechanisms other than increased extracellular HO. genera tion. (C) 1995 Intox Press, Inc.